Vaseline on switch contacts

[PaulR]

I never really believed that Vaseline would help with scratchy volume pots until I tried it on two or three troublesome ones with total success. I mentioned this to a friend who had been having trouble with a slider switch and he decided to try it before replacing the switch. Again, this appears to have been successful.

Can anyone explain how this seems to work, and does anyone have any opinions as to the advisability of trying it on troublesome rotary wave change switches?

Paul

[Sean Williams]

I cant tell you why it works, but I do have a book here that deals with high power distribution.

There is a whole section regarding bolting busbar connections together and using Vaseline between the mating faces, with the supporting claim that this lowers contact resistance.

I can't see that trying a small amount would be detrimental on a wafer switch.

[trsomian]

On bus bar connections it simply keeps the air out and therefore stops the corrosion that airborne moisture causes, I have used a tiny blob of 20/50 engine oil on volume controls before; works a treat, and unlike Vaseline, flows back after the wiper has gone past. I use engine oil on the battery terminals of the car too, a quick wipe over the mating surfaces before fitting the terminals, and then a blob on the top to work its way into any gaps by capillary action

[emeritus]

I also have a book that (briefly) describes the use of Vaseline to bolt Aluminium busbars together, having first filed the surfaces with a rough file, filing through the Vaseline and not wiping it off before bolting. It prevents the instantaneous oxidation of raw Aluminium surfaces that happens when exposed to atmospheric Oxygen. It was also said to be advantageous, but not essential, for joining copper bus bars.

I think it is to do with the fact that lubricating greases are generally mixtures of oil and a chemical soap, and are designed to resist pressure so as to prevent touching surfaces from coming into actual contact. Vaseline is a pure hydrocarbon and, because it does not contain any of the soap that keeps oil in place in lubricating greases, can flow under pressure to allow surfaces to come into intimate contact.

For low voltage stuff I use 3-in-1 oil for noisy pots, and it usually works OK : I did once try it on a TV preset, and it caught fire!

[Bazz4CQJ]

Somewhere on the forum, Bill WME (I think) described adding a pea-sized blob of Vaseline to some quantity of IPA, and thus creating an emulsion (it needs really good shaking before each use) which can be applied using a dropper or cotton bud on contacts. Of course, the IPA evaporates leaving just a nice amount of tiny globules of Vaseline to provide lubrication.

I think that Vaseline is a pure, un-reactive, hydrocarbon, but engine oil has many additives in it (anti-oxidants, phosphates, zinc compounds, detergents etc, etc) and some of those may not be ideal for electrical contacts, but if it works...

Having paid a lot of money for a can of Deoxit, I'm not sure I'll go down that route again when it runs out.

B

[Craig Sawyers]

There is a product for precisely this problem. Caig FaderLube. Google it and filter by UK, and there are lots of hits. A lot more expensive that vaseline though.

I have a can of Caig DeOxit that is a handier household help for cleaning and fixing dirty or noisy switches, the latest fixes being noisy switches on a Tektronix 576 curve tracer and on a Fluke differential voltmeter.

[paulsherwin]

Vaseline is basically very viscous mineral oil. It won't harm contacts. There are various witch's brew concoctions of vaseline, paraffin, diesel, white spirit etc. which advocates argue work just as well as commercial contact cleaners.

The drawback with any cleaner with an oil component (like WD40) is that it will leave an oil film which may attract dust and other contaminants, though it will inhibit corrosion and oxidation.

[Craig Sawyers]

WD40; wait until I get out the garlic and cross.

I'm a member of a teletype forum (greenkeys), and WD40 is the worst possible thing to use. Basically a machine that is sluggish because the grease has got gummy will seize rock solid after WD40. Basically it just washes all the dust and lint into the moving parts and leaves it there. The only solution to that is a complete machine strip (worse than car engine or gearbox), clean and reassemble.

Or on bike chains, where it provides a sticky goo for road dirt to stick to.

The only thing I've ever found it useful for was getting an old style mini going again on a damp morning with a liberal spray of the distributor cap and plug leads. Which is kind of not surprising since the WD stands for Water Displacer.

[ms660]

We used to use a thin smear of MS4 for tuner contacts in TV's for other contacts it was bog standard switch cleaner or a drop of Electrolube, the latter required three signatures from the lord himself to obtain a pen of that from the stores.

Lawrence.

[McMurdo]

There's a particular model of audio product where the cooling fans draw the air in from the front over the control pots, tarnishing the sliding bits. Dismantling them and smearing the innards with vaselne is the only solution I've found. Spraying anything in there doesn't work. Replacing them leads to failure soon after for the same problem. I'm with the theory of preventing oxidation or moisture ingress. We used to have a large tin of 'electrical contact lubricant' made by someone like Rocol (can't be sure, their website makes my PC overheat) and that looked and smelt like vaseline.
If buying vaseline, get the genuine stuff. Some of the cheap brands appear to be aerated/whipped with air to give them more volume.

[Bazz4CQJ]

Originally Posted by emeritus

Vaseline is a pure hydrocarbon and, because it does not contain any of the soap that keeps oil in place in lubricating greases, can flow under pressure to allow surfaces to come into intimate contact.

That's an interesting interpretation and sounds plausible. I'm definitely of the opinion that old switches in particular, respond best if they are not only cleaned, but lubricated also. They then work better, and last longer.

B

[Craig Sawyers]

The worst offender are pro audio amps that live in an environment with stage smoke - the sort of thing that is used in rock concerts to show up the beams from the lights. And theatre for special effects.

I've ended up washing the inside of amps I've bought from that environment to get rid of the sticky goo it leaves inside, along with fluff and grit that sticks to it. Who can tell what it does to stage acts' lungs.

[Terry_VK5TM]

Back in the day, Vaseline was used in high performance RC cars on switching contacts (this was before all the new u-beaut solid state stuff).

Tamiya used to sell it in a (very) small tube called "Switch Lubricant", at what I should imagine was a very healthy profit margin.

Terry

[Craig Sawyers]

Just noticed that Caig do something called Fader Grease, which seems to do something similar to vaseline. In the US $19.95 for a 28g pot. Or £22.50 in the UK. Or about 15 - 20 times the price of vaseline.

Craig

[stevehertz]

For the life of me I cannot see why, when there are excellent, 'designed for purpose' products to remove corrosion, lubricate, prevent further corrosion and extend the life of a pot, that a thousand and one other, petroleum based products are used by those of us who can't or won't buy the proper stuff. Petroleum and plastics/rubber is not a good mix, I've found that out myself to my own dismay. I'd like to see the inside of pot after a couple of decades as the slider skids and lifts (off the track) over lumpy, dirty, tired old Vaseline. Just because something 'works' in the short term, it does not make it the ideal or even perfect product for the job. I'm not talking about busbars, they're a completely different thing that live and operate in a different environment, in fact any comparison in that direction is like two blokes arguing over whether their cars should run on diesel or petrol, when they own one of each. Buy some switch cleaner, it'll cost you less than a couple of pints of beer, it does what it says on the tin, it's perfect for the job and the future of your (and future generations') radio.

[Craig Sawyers]

Originally Posted by stevehertz

Buy some switch cleaner, it'll cost you less than a couple of pints of beer

And that is a good point. I know I am a fan of Caig products, but Servisol and Electrolube are also excellent branded products and available from Farnell and RS

Servisol contact grease is £10.50 plus VAT for 35cc from Farnell. Electrolube SWC200D solventless switch cleaner is £28.82 plus VAT for 200g, again from Farnell.

And if you download Keithley manuals for current products from the Tektronix site, they set out a control lubrication regime using Caig products.

Craig

[PaulR]

In the case of the pots where I have used Vaseline I have previously tried Servisol switch cleaner or completely dismantled them and cleaned the wiper with silver polish and the track with switch cleaner, both of which worked for a few weeks but no longer.

I have read on this forum that Waxoyl also works but I think that the solvent in this would quickly evaporate to leave a hard wax coating. So far the Vaseline has worked very well on pots that would otherwise have been replaced but it has only been there for about 18 months on the one I tried first so time will tell as to how long it will last.

[stevehertz]

Yep, Waxoyl is another example of a totally wrong substance to put on delicate radio switches. It is designed to dry to a - not a hard coating as such - but one that can withstand the rigours of life on the underside of an automobile in all weathers. As you say, it's a "hard wax coating". Now why would anyone want to put such stuff on a switch?! Well, maybe if you wanted the switch to operate under water and were prepared to suffer intermittency. Like I say, just because people use a substance and swear by it, it is not necessarily the best stuff for the job, especially when designed for purpose products are available. Someone I know - a family member actually - was told that cider vinegar was "the best thing that you could take" by a well meaning other relative. Thus began many years of illness caused by complications arising from the taking of daily doses of cider vinegar. People are well meaning when they advise all these things, but in my opinion, without scientific evidence, you're best sticking with stuff has been tested and 'certified' for use.

[John Caswell]

Back in the days of turret tuners in TV, the contacts were the very devil to keep clean for a long period. Everything was tried until we hit upon silicone grease.
Technique was clean all contacts with Carbon Tetrachloride, allow to dry then apply a thin smear of silicone grease, Radiospares (that dates me) did their own brand, problem gone away for at least a year often longer. Used to apply it with Q tips or a clean finger.
Rank Bush Murphy switch cleaner then came into vogue and that was very good also, applied with a small stencil brush on sliding switch contacts in both TVs and radios.

John

[PaulR]

I had never heard of Servisol silicone contact grease and will certainly try that. It is only £7.55 from CPC including the small order handling charge.